I wasn't engaged in the online discussion last night. But looking at photos this morning, the Dillon Reservoir loon has good potential to be an Arctic Loon, which of course would be extraordinary anywhere in the eastern half of North America. It's a challenge to separate Arctic and Pacific loons in any plumage. Typical individuals look distinctly different, but there is variation in both species. There is variation (and some overlap) in all of the characteristics that separate them, so there isn't any one simple yes/no, on/off distinction that would be diagnostic by itself. Here we have to build up a case with as many characteristics as possible, especially for a bird so far outside its normal range. This morning the bird in question was seen by a number of people, and then it was seen to fly away. Still trying to find out whether anyone got photos of the bird in flight. A good, clear photo of the underparts would be helpful in pinning down the ID, but it would also be helpful to have as many photos as possible of the bird on the water, showing things like head shape, bill shape, nape color, pattern of the neck stripes, flank pattern, and so on. A photo with the bird in direct size comparison to a Common Loon would be a bonus. I suspect that the Ohio Bird Records Committee will want to collect materials like this and send them to someone who has really studied loon ID, such as Lars Jonsson. If the bird is indeed an Arctic Loon, the big question would be which source population it represents. The most likely would be the Siberian subspecies, G. a. viridigularis, which nests in n.w. Alaska in very small numbers (and may sometimes interbreed with Pacific Loon, producing intermediates, which certainly makes the ID challenge more interesting). But we can't dismiss the (remote) possibility of a transatlantic vagrant of G. a. arctica coming across from Europe. I wouldn't expect that bird to show up on a reservoir in Ohio, but birds do strange things. At any rate, here's hoping that the bird will be refound so that it can be enjoyed by more birders, and here's hoping that it can be pinned down to a positive identification. Kenn Kaufman Oak Harbor, OH ______________________________________________________________________ Ohio-birds mailing list, a service of the Ohio Ornithological Society. Please consider joining our Society, at www.ohiobirds.org/site/membership.php. Our thanks to Miami University for hosting this mailing list. You can join or leave the list, or change your options, at: listserv.miamioh.edu/scripts/wa.exe?LIST=OHIO-BIRDS Send questions or comments about the list to: [log in to unmask]